docs: def save_to_txt(self, path='./', name=None,
                      include=['Mod','Cls','Exp','Name'],
                      fmt='%.18e', delimiter=' ',
                      footer='', encoding=None, verb=True, return_pfe=False):
          """ Save the basic geometrical attributes only (polygon and pos/extent)
  
          The attributes are saved to a txt file with chosen encoding
          Usefu for easily sharing input with non-python users
  
          BEWARE: doesn't save all attributes !!!
          Only saves the basic geometrical inputs !!!
          Not equivalent to full tofu save (using self.save()) !!!
  
          The saving convention is:
              * data is saved on 2 columns
              * The first line gives 2 numbers: nP, no
                  - nP = Number of points in the polygon
                      (i.e.: the number of following lines describing the polygon)
                  - no = Number of occurences (toroidal if in toroidal geometry)
                      (i.e.: the nb. of pos/extent lines after the first nP lines)
              * Hence, the data is a 2D array of shape (1 + nP + no, 2)
              * The two columns of the nP lines describing the polygon represent:
                  - 1st: R (resp. Y) coordinate of polygon points
                  - 2nd: Z (resp. Z) coordinate of polygon points
              * The two columns of the no lines representing the occurences are:
                  - 1st: pos, the tor. angle (resp. X) center of occurences
                  - 2nd: extent, the tor. angle (resp. X) extension of occurences
  
          Hence, the polygon and pos/extent of the object can be retrieved with:
          >>> import numpy as np
          >>> out = np.loadtxt(filename)
          >>> nP, no = out[0,:]
          >>> poly = out[1:1+nP,:]
          >>> pos, extent = out[1+nP:,0], out[1+nP:,1]
  
          All parameters apart from path, name and include are fed to numpy.savetxt()
  
          Parameters
          ----------
          path:   None / str
              The path where to save the file
              If None -> self.Id.SavePath
          name:   None / str
              The name to use for the saved file
              If None -> self.Id.SaveName(include)
          include:    list
              List of attributes of to be used to built the default saving name
              Fed to tf.utils.ID.generate_SaveName()
              Recommended: ['Mod','Cls','Exp','Name']
          """
          if name is None:
              name = self.Id.generate_SaveName(include)
          if path is None:
              path = self.Id.SavePath
          path = os.path.abspath(path)
          pfe = os.path.join(path,name+'.txt')
  
          nPno = np.r_[self.Poly.shape[1], self.noccur]
          poly = self.Poly.T
          posext = np.vstack((self.pos, self.extent)).T
          out = np.vstack((nPno,poly,posext))
  
          # default standards
          newline = '\n'
          comments = '#'
          header = ' Cls = %s\n Exp = %s\n Name = %s'%(self.__class__.__name__,
                                                       self.Id.Exp, self.Id.Name)
  
          kwds = dict(fmt=fmt, delimiter=delimiter, newline=newline,
                     header=header, footer=footer, comments=comments)
          if 'encoding' in inspect.signature(np.savetxt).parameters:
              kwds['encoding'] = encoding
          np.savetxt(pfe, out, **kwds)
          if verb:
              print("save_to_txt in:\n", pfe)
          if return_pfe:
              return pfe